Meters for fluidic resources such as, for example, water and gas meters are frequently arranged in the immediate vicinity of the supply systems for the fluidic resources and therefore directly exposed to adverse external conditions such as moisture, dirt and temperature fluctuations. In the past, reliable and cost-efficient mechanical metering mechanisms, which were able to ensure a long service life, were frequently used in such meters, particularly in water meters, in order to protect against these adverse ambient conditions. However, mechanical metering mechanisms have the disadvantage that the readout of the meter readings typically has to be carried out visually by a person at the installation site of the meter and therefore is labor and cost-intensive.
Consequently, various electronic meters, which are connected to a network, are nowadays used such that the readout of the digital meter readings of the meters can be realized by a central database via the network. These network-bound applications frequently are also collectively referred to as “Smart Metering.”
In order to ensure the functionality of the electronic meters, the electronic meters not only require an energy supply, but the meters also have to be connected to the network by means of suitable and reliable interfaces in order to transmit the meter data. In the prior art, the energy supply was either realized by means of an internal power source such as a battery or by means of a permanent electrical power supply as described, for example, in EP0293639 A2.
If an internal power source such as a battery is used for the electronic metering mechanism, the service life of the electronic meter is primarily defined by the service life of the internal battery. In order to protect the power source from environmental influences, the power source and the electronic metering mechanism usually are hermetically encapsulated such that the power source cannot be readily exchanged, wherein meters with a power source in the form of an internal battery are therefore only used to a limited extent. If the energy supply and the data link are respectively realized by means of electrical power and data cables, sealing problems frequently arise within the cable leadthroughs due to aging processes and fatigue of the materials used, particularly the sealing material.
In addition, there also exist alternative meters with radio applications, by means of which at least a wireless data transmission from the hermetically encapsulated metering mechanism to a readout device arranged outside the metering mechanism can be achieved. However, the electrical energy supply for such meters with radio applications is frequently still realized with internal power sources such as batteries and wire-bound cable connections as described, for example, in US 2014/0045550 A1.
Furthermore, there also exist completely wireless energy supply and data transmission systems for meters such as, for example, Radio Frequency Identification—or RFID—applications. In this case, an RFID transponder is integrated into the hermetically encapsulated metering mechanism of the meter, wherein the RFID transponder features an antenna, an analog receiving and transmitting circuit, as well as a digital circuit and a non-volatile memory. The readout device assigned to the RFID transponder generates a high-frequency electromagnetic alternating field that is picked up by the antenna of the RFID transponder and activates the electronics of the RFID transponder in accordance with the meanwhile standardized RFID method. In this case, the readout device simultaneously sends communication and control commands that are picked up and additionally processed by the RFID transponder. The detection of the respective RFID transponder in the readout device is ensured, for example, in that the RFID transponder encodes the signal response to the readout device and models the electromagnetic field in the irradiated electromagnetic field of the readout device by means of field shunting or anti-phase reflection in order to thereby transmit its own unchangeable serial number, additional data and other information requested by the readout device. After the data transmission from the RFID transponder to the readout device, the data link between the RFID transponder and the readout device is once again separated by means of a standardized method and the energy transmission from the readout device is subsequently interrupted.
For example, JP2008015855A describes an RFID transponder system for a meter with communication functions, wherein a wireless and reliable data transmission from the meter to the readout device is ensured by purposefully controlling the transmission rate of the meter.
In conventional RFID transponder systems, however, it is problematic that a circular polarization of the high-frequency electromagnetic alternating field is frequently required due to different positioning of the readout device relative to the RFID transponder, wherein such a circular polarization requires high radiation energy of the electromagnetic alternating field and results in a long energy transmission and data link period. Furthermore, the fluidic resources, particularly water, absorb the radiation energy of the electromagnetic alternating field and an additional reflection of the electromagnetic alternating field takes place on the usually metallic components of the meter such that only a fraction of the radiation energy of the electromagnetic alternating field reaches the readout device of the RFID transponder. Consequently, high radiation energies of the electromagnetic alternating field emitted by the readout device are required for the energy transmission to the RFID transponder, as well as the data link therewith. Even if the electromagnetic alternating field emitted by the readout device has a very high radiation energy, the wireless energy transmission or the subsequently established data link may still be faulty if the readout device is unfavorably or variably positioned relative to the RFID transponder such that the connection and therefore the time-intensive data link between the readout device and the RFID transponder in accordance with the RFID standard have to be established anew.
Another disadvantage of solutions known from the prior art can be seen in that previous cable-bound or wireless meter systems cannot simultaneously ensure an effective energy supply for the hermetically encapsulated meter and a reliable and stable data link between the readout device and the hermetically encapsulated meter. One particular disadvantage of RFID transponder systems in meters can be seen in that the energy supply of the RFID transponder can only be realized with very high radiation energies of the electromagnetic alternating field emitted by the readout device, which in turn leads to a high power consumption of the readout devices. The energy and data link has to be established anew very frequently due to inaccurate or variable positioning of the readout device relative to the RFID transponder such that the power consumption of the readout device is additionally increased and the readout of the data from the RFID transponder is respectively delayed or prevented.